1. Field of the Invention
This invention relates to an image pickup apparatus and method, and more particularly, an image pickup apparatus and method for preventing cumulative addition of image signals for which camera-shake correction is insufficient, and for improving picture quality of image signals stored in memory.
2. Description of the Related Art
Various forms of camera-shake prevention technologies for preventing blurring of images resulting from vibration due to movement of a camera operator and preventing degrading (blurring, dislocating) of recording images have been proposed for image pickup apparatus such as digital still cameras and video cameras capable of taking and recording images in the related art.
For example, an image pickup apparatus that detects an amount of dislocation in the event of taking a picture from an image (still image) captured over a prescribed period or prescribed number of times and then records images (still images) for which the dislocation amount is the smallest has been proposed, and described in, for example, Japanese Patent Application Publication No. Hei. 11-317904 (at page 11-12, FIG. 1, FIG. 26).
However, as shown in FIG. 7A, it is preferable for image pickup apparatus that cumulatively add picked up image signals for storage in memory to ensure a sufficient maximum value (herein after referred as maximum correction amount) for the correction amount in order to correct camera-shake completely so as to enable cumulative addition. However, in reality, as shown in FIG. 7B, cumulative addition only achieves camera-shake correction up to the maximum correction value for image signals which exceed the maximum correction amount, and blurred and overlapping (dislocated) images are therefore stored in memory.
Further, as the recording size of image signal (hereafter referred to as recording image size) is set in advance, when recording image size is set to be large against the range for which pictures can be taken by the image pickup element (hereafter referred to as possible image size), the range in which camera-shake correction is possible (hereafter referred to as correction range) becomes small, and the ends of the correction range are reached even for comparatively small camera-shake vibrations.
As an image signal corrected at the ends (hereinafter, correction ends) of the correction range is an image signal corresponding to the straight line parts of FIG. 7B, so the camera-shake correction processing is insufficient, when an image signal corrected at the correction ends in this manner is cumulatively added, images in a blurred or overlapping (dislocated) state are stored in memory.
Therefore, there is the problem to be resolved for image pickup apparatus having means for cumulatively adding image signals and storing the image signals in memory, with respect to preventing cumulative addition of image signals for which camera-shake correction is insufficient, and improving picture quality of image signals stored in memory.